I’m with Kristijan. Its often done, to pour aluminum around steel. Great pattern work, btw.
Rindert
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That is beautiful woodwork
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I totally need to do that… I keep finding half full propane tanks. I think I picked up 4 or 5 of them in the last 2 weeks curb shopping. (some were empty.)
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In this video, he squirts some liquid on the mold and lights it. Why?
My guess is to bake the surface into a bit of shell. I think they are using molasses for a binder.
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I think the purpose of lighting the liquid is to dry the sand so no steam/gases form when pouring.
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So FINALLY the core box is done. I confess, tis thing has tested my patience! Just a coat of sealer an try it out.
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Yes! Pattern work is the most challenging aspect of foundry. Your work looks very good though. What kind of binder do you use for your cores? I like washed silica sand, 120 grit, with waterglass/ CO2.
Rindert
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I use the waterglass co2 also. So far, ive just made the co2 with vinegar and baking soda.
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I have a tank and regulator. I hooked up a spray gun like for the kitchen sink and pushed a short piece of hose over the nozzle. The grocery store sells dry ice. I just get some and put it in there when I run out.
Rindert
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Can someone plese explain that waterglass CO2 method in more detail plese? Never heared of it…
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Water glass is an old fashioned name for sodium silicate. You might remember a previous discussion by that name.
Anyway you would mix a small percentage ( about 5% ) sodium silicate with the sand, then press into the mold. When carbon dioxide is applied, it hardens instantly. No baking, no waiting.
While i’m at it, here is my co2 generator.
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Yes l use waterglass a lot but never heared of it hardening with CO2! This opens so many posibilitys!
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I think you did use CO2 before. When you put insulation inside your chargas generator for your MBZ e230 you used a torch to harden the waterglass. The torch makes CO2.
Rindert
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I admire you remembering my waterglass/rockwool experiment but l cant seem to remember pre hardening it, except with the gasifier it self. Culd be old age 
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I suspect that liquid is “diesel” or a fuel oil. According to wikipedia it is also used as an additive for a reducing agent which prevents the metal from sticking to the sand. The way it is burning, it looks like some was already in the sand. My guess is if you pour hot metal into a closed cavity with diesel in it, it results in the diesel catching fire and blows the aluminum out of the cavity.
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Lights a bit to easy for diesel. Maybee kerosene?
Culd it allso be burnt to soot the surfacem
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I think Kristijan has the right answer. I have seen a mold maker dust the inside surface with powdered graphite. It made a very smooth surface on the casting. And Petrobond sand contains oil and makes beautiful smooth surfaces.
Rindert
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The first attempt at a core was not entirely successful, but showed some promise. I think i needed to be more gentle with the removal. I waxed the core box with paste wax, and it didnt seem to stick too bad. Would dry powder be better for release?
Why dont I start out learning on a simple project like a normal person?
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